PRINTING BLANKET HOLDING BAR FASTENING METHOD

PROCEDE POUR FIXER UNE BARRE DE RETENUE SUR UN BLANCHET D'IMPRESSION

English Abstract

This invention is a method for
securing a mounting bar (4) to a
printing blanket (6) by applying a strip
of a hot melt adhesive tape (7) along
and adjacent am edge (5) of the blanket
(6), placing the mounting bar (4) along
the edge (5) of the blanket (6) upon
the tape (7) to form am assembly,
and applying heat and pressure to the
assembly for a sufficient time to melt
the adhesive (7) and securely attach
the mounting bar (4) to the blanket
(6). The assembly may be cooled to
more rapidly solidify the adhesive (7)
so that the assembly can be placed
into service without waiting for a long
adhesive curing time.

French Abstract

Cette invention se rapporte à un procédé qui permet de fixer une barre de montage (4) à un blanchet d'impression (6) et qui consiste à appliquer une certaine longueur d'une bande adhésive thermofusible (7) le long d'un bord du blanchet (6) et à proximité adjacente de ce bord, à disposer la barre de montage (4) le long de ce bord (5) du blanchet (6) et à la placer sur la bande (7), afin de former un ensemble, puis à appliquer chaleur et pression sur l'ensemble pendant une période suffisante pour faire fondre l'adhésif (7) et fixer de façon sûre la barre de montage (4) au blanchet (6). L'ensemble ainsi obtenu peut être refroidi pour que l'adhésif (7) se solidifie plus rapidement, ledit ensemble pouvant ainsi être mis en service sans qu'il soit nécessaire d'attendre longtemps avant que l'adhésif ne durcisse.

Claims

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THE CLAIMS
What is claimed:
1. A method for securing a mounting bar to a
printing blanket which comprises:
applying a strip of hot melt adhesive tape
along and adjacent an edge of the blanket;
placing the mounting bar along the edge of
the blanket upon the tape to form an assembly;
applying heat and pressure to the assembly
for a sufficient time to melt the adhesive and provide
a substantially uniform thickness of such adhesive
between the components; and
allowing the melted adhesive to solidify and
securely attach the mounting bar to the
blanket.
2. The method of claim 1 which further
comprises selecting the hot melt adhesive tape to be
of a thermosetting or thermoplastic material in the
form of a flat strip.
3. The method of claim 1 which further
comprises selecting the hot melt adhesive tape to be
of a polyurethane or nylon material in the form of a
flat strip.
4. The method of claim 1 wherein the blanket
comprises a top printing surface and a bottom support
surface, and which further comprises applying the
adhesive tape to the bottom support surface of the
blanket.
5. The method of claim 1 wherein the holding
bar comprises upper and lower spaced legs each having
a surface for contacting the blanket and which further
comprises inserting the blanket edge and adhesive tape
between the surfaces of upper and lower legs of the
mounting bar before applying heat and pressure
thereto.

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6. The method of claim 5 wherein sufficient
pressure is applied to the assembly to force the
surfaces of the upper and lower legs to substantially
completely contact the edge of the blanket.
7. The method of claim 6 wherein sufficient
heat is applied to the bar to melt the adhesive tape
so that the adhesive can melt and solidify to join the
bar to the blanket.
8. The method of claim 7 which further
comprises cooling the assembly to harden the adhesive
and reduce the time within which the assembly can be
mounted upon a printing cylinder.
9. The method of claim 4 which further
comprises applying a second hot melt adhesive tape to
the top surface of the blanket along an adjacent the
edge thereof.
10. The method of claim 9 which further
comprises selecting the second hot melt adhesive tape
to be of a thermosetting or thermoplastic material in
the form of a flat strip.
11. The method of claim 9 which further
comprises selecting the second hot melt adhesive tape
to be of a polyurethane or nylon material in the form
of a flat strip.
12. The method of claim 1 wherein the bar is
heated to about 180°C to melt the adhesive tape.
13. The method of claim 9 wherein the bar is
heated to about 180°C to melt the adhesive tape.
14. The method of claim 1 which further
comprises selecting the mounting bar to be of a heat
conductive metal.
15. The method of claim 1 which further
comprises selecting the mounting bar to be of
aluminum.

Description

WO 9512I06i PCT/US95/oil8o
PRINTING BLANKET HOLDING BAR FASTENING METHOD
TECHNICAL FIELD
This invention relates to an assembly for
mounting and holding a printing blanket in a printing
press cylinder. More specifically, this invention
relates to a method for fastening the holding devices
or bars used to hold such printing blankets on the
printed cylindrical rollers.
BACRGROBND OF THE INVENTION
Sheet-fed printing presses are widely used in
lithographic printing. In these presses, printing
blankets are utilized to pick up the inked image from
the printing plate and then transfer this image onto
the paper which is to be printed. These printing
blankets are comprised of an outer layer, formed
mainly of a polymeric material, and a backing material
on one side of the outer layer. The other side of the
outer layer is the printing surface which carries ink
for printing. The blanket is wrapped on a cylinder to
transfer an inked image from a printing plate to paper
during the printing process.
To achieve high quality printing, the blanket
must not slip or creep on the cylinder. The
conventional method of securing the blanket to the
cylinder has been to secure the leading and trailing
edges of the printing blanket between a channel formed
into a holding bar. This holding bar is then housed
j in a gap or groove extending axially along the surface
of the cylinder.
A number of considerations must be kept in mind
when mounting these blankets to the holding bar, the
foremost of which is to make sure that the printing

WO 95121061 PCT/US95101280
- 2 -
blanket will not separate from the holding bar when
the blanket is stretched taut over the printing
cylinder. Another factor is the simplicity of !
installation and time involved in attaching the
printing blankets. Conventional methods utilize a
mono or bicomponent glue such as epoxy or polyurethane
resin which is viscous and difficult to apply evenly.
Furthermore, there is about a 24 hour delay between
the apglication of the glue and bar to the blanket for
1o curing prior to actual use.
Accordingly, there is a need for fastening a
holding bar to a printing blanket in an expedient and
inexpensive manner so that it will be able to bear the
necessary mechanical stresses due to tensioning the
blanket on the cylinder.
SUMMARY OF THE INVENTION
The present invention constitutes an improvement
over the prior art as described above. In accordance
with the present invention, a strip of an adhesive
tape made of a thermoplastic or thermosetting hot melt
material such as polyurethane or nylon is used to
firmly bond the printing blanket to the holding bars.
This method according to the invention is well
calculated to single-handedly perform the job of
assembling a holding bar to a printing blanket. Thus,
according to the invention, the adhesive is directly
applied in the form of a strip upon the edge of the
printing blanket. Thereafter, a holding bar is placed
adjacent the adhesive strip, and sufficient heat and
pressure are utilized to melt the adhesive. Upon
heating, the adhesive forms a layer of substantially
uniform thickness between the holding bar and the
printing blanket; and adheres to both the bar and the

WO 95/21061 ~~ ~ ~ pCT/US95/01280
- 3
blanket. The adhesive then establishes a firm bonding
between these components on subsequent cooling.
The above and other features and advantages of
this invention and the manner of attaining them will
become more apparent, and the invention itself will
best be understood, from a study of the following
description with reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a fragmentary perspective view of a
holding bar.
FIG. 2 is a perspective.view of an unwrapped
printing blanket and a layer of thermosetting
adhesive.
FIG. 3 is a side view of the printing blanket of
FIG. 2 in between the legs of the holding bar of FIG.
1 and positioned in a heating station.
FIG. 4 is a side view of the printing blanket
being fastened to the holding bar by the heating
station.
FIG. 5 is a side view of the bar and printing
blanket assembly being cooled.
DETAILED DESCRIPTION OF THE INVENTION
The term "hot melt" as used herein should be
understood to mean any solid, thermoplastic or
thermosetting adhesive which melts upon application of
heat and then sets to a firm bond on cooling. Besides
providing a sufficiently strong bond between the
printi~-- blanket and the holding bar, the adhesive
layer 4~4rebetween can be remelted, if desired, after
the use of the printing blanket, for example, to allow
removal of the holding bar in reusable form.
With reference to FIG. 1 of the drawing, a
typical holding bar in accordance with the invention

WO 95121061 ~ PCTIUS95101280
- 4
is shown. The holding bar is typically in the form of
a channel-like member having a bight 3 and a pair of
legs 1 and 2 diverging outwardly from apposite ends of
the bight. The holding bar is adapted to be deformed
so that the legs 1 and 2 are arranged substantially
parallel-as illustrated in FIG. 1.
For the preparation of the holding bar and
printing blanket by the method of this invention, a
strip of hot melt adhesive 7 is applied to part of at
least the top surface of the printing blanket 6. The
adhesive 7 is preferably applied to the printing
blanket 6 by unrolling a tape supply 8 and placing it
along the edge of the bottom surface of the blanket 6.
Thus, one embodiment of the invention includes a tape
supply 8 and scissors apparatus 9 for cutting the tape
for easy application to the printing blanket 6 as
shown in FIG. 2.
After the adhesive 7 has been applied on the
printing blanket 6, the printing blanket 6 is placed
in between legs 1 and 2 of holding bar 4. The legs of
the holding bar 4 are moved apart in the area S where
leg 1 adjoins bight 3 as shown in FIG. 3. This allows
the edge of the printing blanket 6 to be positioned
closely adjacent to bight 3 and preferably against the
inside surface of such bight. The holding bar 4 can
be slipped onto the printing blanket 6 immediately
after, or concurrently with, the travel of the
adhesive 7 rolled down the edge of the printing
blanket 6.
The holding bar 4 and the printing blanket 6 are
then fitted on the lower plane 10 of the heating
station (limit switch) and the top plane 11 of the
heating station is fitted over the top end of the
holding bar as shown in FIG. 3. This station applies
both heat and pressure to the assembly pressure is

W0 95121061 PCT/US95JOI280
- 5
applied by lowering the upper plane 11 until the
necessary force is applied to close the holding bar 4
at the required thickness as shown in FIG. 4. The
holding bar 4 is then maintained in this position as
long as the heat coming from the upper plane 11 is
transmitted to the holding bar 4. The heat is applied
to melt the adhesive tape so that it can adhere to
each component. Generally, a temperature of about
180~ is sufficient to do this.
The preferred adhesive strips are those which are
hot melt adhesives of a thermosetting or thermoplastic
nature, such as nylons or polyurethanes. Other hot
melt adhesives are known to those skilled in the art
and can also be used. At room temperature, these
adhesives are solid and can be formed into desired
shapes. For this invention, it is preferably to
utilize flat strips of adhesive which have a uniform
thickness and a width which corresponds to width of
the legs of the holding bar. This enables a
substantially uniform thickness of adhesive to be
applied in the appropriate locations in a simple and
straightforward manner, thus highly simplifying the
manufacturing process compared to the use of liquid or
semi-solid adhesives.
Moreover, the application of a substantially
uniform thickness of the adhesive enables increased
bond strengt:~~ to be obtained between the holding bar
4 and the blanket 6. Since the adhesive is a solid at
room temperature, it is easy to handle and accurately
place on the blanket. It also facilitates placement
in the holding bar without initially sticking to the
legs of the bar or otherwise being displaced
inadvertently. The closing of the legs of the holding
bar onto the adhesive strip and blanket also retain
the position of the adhesive without squeezing or

WO 95121061 PCTIUS95101280
6 -
extruding it into undesired locations. Thereafter,,
the heat which is applied causes the adhesive strip to
melt and adhere to the bar and blanket at a
substantially uniform thickness for maximum bond
strength. Also, the connection can be made easily and
quickly, so that the blanket can be used minutes after
being made, rather than in 24 hours when liquid
adhesives are used.
Finally, referring to FIG. 5, the upper plane 11
is lifted and the now barred blanket is taken off and
forced to cool in a cooling station 2o and 21 which
solidifies the adhesive 7 and provides a firm bond
between the bar and the blanket. After cooling of
holding bar 1 and printing blanket 6, the bar and the
blanket are able to bear the necessary mechanical
stresses due to tensioning in the cylinder, and can be
immediately used.
The holding bar or similar bar may be made of any
suitable material. Preferably the holding bar is made
of an easily deformable, heat conductive, non-ferrous
metallic material such as aluminum. Further, it will
be appreciated that the holding bar may be of any
suitable construction and reference is made to U.S.
Pat. No. 3,883,940, for example, for a disclosure of
holding bars of other materials and designs.
As has been mentioned in connection with the
method of this invention, the printing blanket and/or
the holding bar can be heated and provided with a hot
melt adhesive in various ways other than those adopted
in the embodiments of FIGS. 3-5. The applications and
heating method of FIGS. 3-5 is preferred, however,
because of the quickness of assembly, the ease with
which the printing blanket is heated and coated, the
constancy of the bar temperature, and the uniformity
of the thickness of the resultant adhesive layer.

WO 95121061 PCTlUS95101280
Furthermore, the fitting of the holding bar over the
printing blanket immediately after the application of
the adhesive strip onto the latter, as in this
embodiment, contributes to the uniformity of the
thickness of the adhesive to thus provide a firmer
union therebetween.
While present exemplary embodiments of this
invention, and methods of practicing the same, have
been illustrated and described, it will be recognized
that this invention may be otherwise variously
embodied and practiced within the spirit and scope of
the following claims.
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Representative Drawing